Fan



July 19, 1.9312.A A. D. GARDNER FAN Filed April 4, 1931 `2 Sheets-Sheet 2 INVENTR a0 @m0/vae ORNEY Patented July Y 19, 1932 UNITED STATES VPA'PENT N ori-Ica ARCHIBALD .'D. GARDNER, 0F JACKSON, MICHIGAN, ASSIGNOR TO.A`UTOMOTIVE FAN &

` BEABIN G O0., CORPORATION 0F MICHIGAN FAN ' Application led April 4,

This invention relates to devices for producing a ow of air, such as fans for automotive devices and for other Cooling purposes.'

An object of the invention is to decrease .apparent noise of fans used for the above.

mentioned purposes.

Another object 'is to'increase the air flow vproduced by the fan.

Another object of the invention is to decrease the'apparent noise by constructing a fan with blades having 'dissimilar spacing,

' of Fig. 3.

projected width, shape, or curvature, combination of these features.

Still another object is to obtain an increase of air liow by employing fans with one, or any combination, of these feature Other objects of the invention wi l appear in the following description, reference being had to the drawings in which:

Fig. 1 illustrates the dominant sounds of a four blade fan, illustrating the relation between the sound intensity and angle between blades.

Fig. 2 illustrates curves of air vdelivery and required power.

Fig. 3 illustrates fans with blades having different projected width.

Fig. 4 illustrates fans with blades having different blade shape or outline.

Fig. 5 illustrates fans with blades having different curvature.

' Fig. 6 is a section taken on the line 6 6 or any Fig. 7 is a section taken on the line 7-7 of Fig. 3. 4

Fig. 8 is a section taken on the line 8-8 of Fig. 5.

Fig. 9 is a section taken on the line 9-9 lof FigJ.. l

In the automotiveindustry greater stress.

is being placed upon the elimination of noises in fan having been one source of such noises. In

so that the fan noise the automotive power plant, the coolingr 1981. Serial No. 527,679.

my researches I have discovered how to reduce these fan noises and to reduceV the noise of the engine as awhole by harmonizing the fan the power plant.

Alr requirements of fans are being constantly increased as performance requirements of the engine are i11- creased. increasingly large amounts of air through the radiator core, and at the same time to reduce the noise of the fan toja volume comparable to, or even less than, other noises present in the power plant or other units.

n some cars I have found it practically impossible to eliminate noise with conventional types of fans; in fact, I have found in certain installations, practically no difference in volume or intensity of fan noise, between an extremely noisy fan (on some other installation) and a quiet fan, proven to be eminently satisfactory, on another installation. The fan and the parts surrounding it thus seemed to comprise a combination which was but little affected by changing from one fan to another of the same conventional type. Since an appreciable reduction in fan noise appears impossible under such conditions, li produce apparent quietness by altering the noise characteristics of the fan blends, or merges, with the power plant noises at the speeds and under the operating conditions where it is outstanding. This is accomplished to varying extent in several ways:

1. Changing of the angular spacing of the fan blades about the axis of rotation'.

2. Changing the projected width of some autbmotive cooling I have discovered how to deliver' cycles cycles per second; ier a tour-blade tan the `lundainental frequency is twice as great, or

4 X ian (d0 l cycles per second, lor a six-blade tan,

oX'lanHdPlvl.

cycles -per second.

For example, a tno-blade lan gives iorth the tone B of l2() cycles (in the bass cle-t) at about 360() R. M g a tour-blade tan gives forth as a fundamental the tone oi 240 cycles (bass clef) at about 3600 lt. l). ll/l.; a six-blade fan the 'tone c (middle) at about 2560 R. ll). ll

rThe four-blade ian is in reality two two'- blade fans, and the fundamental sound given forth may be considered as made up of sound having frequency oil (fr) LX litfljll/l. d@ cycles per second (tour-blade vvhine) and (d) per second (two-blade roar). When the angle between adjacent blades is90 def grecs, then the intensity of the two-blade sound becomes a minimum, as shown by the curve 2 under ian adjustment A. of Fig. 1, and intensity of the sound Wave ot four blade frequency is represented by the curve l.

'lhe tour-blade sound thus strongly predominates when the blades are 90 apart. As the tan blades are shifted to gradually decrease the angle a at B, C, D and E, the intensity of the four-blade sound, decreases and the intensity ot the two-blade sound, in-

- creases,

until at F the twoblade sound is a maximum and the tour-blade sound is a minimum. At this position the two pairs oi blades may be considered as having merged into one. lt will be seen that the so-called four-blade sound is in reality the octave of the two-blade sound similarly the corresponding component of a sin-blade lian is the double octave.

llor positions A, B, and C, the higher -trequency four-blinde sound is dominant While for positions D, E, andv l?, the lovverpitched two-blade sound is dominant.

ln determiningv the most suitable angle to be used for any given installation, the'rst step is to observe the noise characteristics oi the power plant under various conditions of speed and throttle opening Without the ian. Thiscan be done by comparing the pitches neeaooe ozt the various noises with a tuning fork, or by actually measuring the noises with one o the more elaborate recording instruments, oi Whichthere are a number available.

The second step is to install the lan and take the same observations on the ian.

.il comparison of the nlreenencies of the sounds es determined above will enable the observer to speci'ly rather closely the most suitable angle, alter which l'die enact angle can be determined by check runs, the object being to adjust the lan so that its dominant sound or noise will be the saine as the domi nant noise olf the engine or an overtone that harmonizes therevvith.

l Making the above observations and coinparisons is sometimes somewhat involved so that tor general use it is leest to employ the cut-and-try method of melting observations 4for a given blade position, then repeating for a slightly different angular spacing1 of blades until the Whole lield ci engularity is covered` noting the combined engine-lan noise effect for each set-ting. @ne may then re-test two or three positions of best noise results to determine the exect angular setting.

lin some cases changing angular spacing?J oi blades as little as one degree makes a noticeable difference in the to which the ian sound stands out above the other noises. While on other installa-tions a change of live degrees is necsary to shovv a change in noise characteristics.

As regards the eilect o angular spacingr oi blades on the quantitv oi air delivered by the lian, it has been lound on a certain tour-blade lian, "for instance, that the air dow does not drop od, in iact actually increases, as the angle is changed from d0 degrees to about 75 degrees. For angles below 7 5 degrees the air flovv drons rather rapidly. rlhis is shown in lliig. 2 Where 3 indicates the curve oi' air llovv and el the curve oil horse power. The horse power requirements lollovv the air tlow curve rather closely over a rather vvide range oi values ot angle between blades.

llnstead of varying,r the single betvveen the blades, one may secure similar results by designing one pair of blades with Ione value of projected Width and the other pair (in a four-blade ian) with a different value of rejected width; also, one may make one pair oi blades with a certain shape, say with parallel sides, and another pair with a diderent shape, say, vvith converging or diverging sides; likewise, one may construct one pair of blades with one particular curvature and the other pair with still another curvature.

ln Figs.. 3, d and ll have shown a lan with equal angular spacings. lhe blades of each opposed pair have the same projected width but tl'ie projected 'Width of one pair a: is dii-- "ferent trom the proiected-vvidth y of the other pair.

Vln Fig. 4 I have shown a four-,blade fan dii lll

- name to this specification this i'irst day of' in which the blades of same shape but each shape than the other.

In Figs. 5, 8 and 9 I have shown a fourblade fan in which one pair of similarly curved blades has a different curvature than the other pair;

each pair have the pair has a di'erent In harmonizing the noises with fans hav-4 ing blades of different projected width, shape or curvature one may follow the method a1- ready outlined in connection with fan blades having different spacing.

It will be apparent that one could vary still other features of the fan blades to produce a variation of tone. The various features I designate as characteristics of the blades.

When a particular type fan has been fitted to a particular type engine it can be used as standard equipment for al1 lengines of the same construction.

While I have illustrated fans with variation of only one feature or characteristics in each of the iigures, similar results can be obtained byvarying two or more of' the fea tures oi' the blade.

Il' have illustrated fans with opposite blades so as to have static balance but the same result can be obtained by using an uneven number of blades Where the blades Will not be directly opposite. In such cases the characteristics can be varied While still obtaining static balance by the inherent position of the blades.

While l have described this invention with particular reference to cooling fans, it will be apparent that to propellers in airplanes and the claims are not to be limited to any particular device.

The fan construction per se is not claimed herein. llt is made the subject of a divisional application filed June i', li932, Serial No. 615.813.

Having claim is:

l. lln combination, an engine having certain dominant sounds, a member rotated thereby and a plurality of fan blades attached to said member and pom'tioned to produce dominant sounds combining with the iirst mentioned dominant sounds to produce minimum resultant noise.

2. In combination, an engine having certain dominant sounds, -a member rotated thereby and a plurality of blades attached to said member to rotate in sumantially the same circular path and unequally spaced to produce dominant sounds` combining with the .l

described my invention, what l rst mentioned dominant sounds to produce minimum resultant noise.

In testimony whereof, I have signed my Aprn, 1931.

ARCHIBALD D. GARDNER.

the same principle applies 

